I have the following working code. This displays a drop down and also fetches a html file to be displayed:
$.getJSON(\'json/shares.json\', function(data) {
Well for the first point you could just run
$('#shares').on('change', function(){
var val = $(this).val();
//submit another ajax request with this value, and get the relevant page, then you'd just need to parse it for the appropriate content from that page.
});
If you want to parse the returned page and get only part of this we'd need to know the markup structure.